I'm fairly ignorant about electronics, but I'm learning. I've been searching and reading. I'm seeking feedback from those who have tackled a similar project. My quandary at this point is which type of sensing setup(s) to use. Laser, IR, sonic, or ?
Situation: I have a garden area that is approximately 35' by 15', somewhat irregularly shaped (as in sensors can't easily be set up in a simple rectangle).
Goal: Detect cats entering the garden, then trip a relay that activates whatever deterrent (yet to be determined -- 120v, or maybe 12v actuated). Avoid false positives, which is important. I have tried using a store-bought, PIR detector that emits high frequency sound. It triggered too often. Plants or shade from nearby tree limbs blowing in a mild breeze were enough to set it off.
Ideally, I'd like to have multiple detection zones so the scary thing that activates is closest to the actual point of intrusion.
Additional benefits: Gives a good home to a shelter / rescue / soon to be executed dog. Keeps other garden unfriendly critters away. Companionship. Entertainment. Excrement is fertilizer.
A good shelter will even steer you towards a cat-unfriendly dog.
Some people have had success deterring deer with an [u]motion activated sprinkler system[/u]. I don't know what the detection range or water squirting range is (and I haven't looked at the specs) but you might need more than one. And the shape of your garden may require more than one.
I know they can be a nuisance, but I like cats. The best defence is to get a cat of your own. They tend to be territorial.
I think I have heard of this..... but don't you then need to swallow a dog, and subsequently a goat to catch the dog which she swallowed to catch the cat she swallowed to catch the bird etc etc
Goal: Detect cats entering the garden, then trip a relay that activates whatever deterrent (yet to be determined -- 120v, or maybe 12v actuated). Avoid false positives, which is important. I have tried using a store-bought, PIR detector that emits high frequency sound. It triggered too often. Plants or shade from nearby tree limbs blowing in a mild breeze were enough to set it off.
Ideally, I'd like to have multiple detection zones so the scary thing that activates is closest to the actual point of intrusion.
Any suggestions what to try or to avoid?
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Now that we have all had fun with the OP, here is my input. I have used a trail camera that is triggered by movement. It does detect our cats and strays, but also detects moving vegetation, coyotes, rabbits, stray dogs, etc. so that won't work for you.
Fencing the garden with 6' high chicken wire will stop all but the most determined cats. The fence needs posts and if they are wooden, the cat will go up them.
I guess I would plant some cat nip in a place away from the garden and make a nice place for them to dig and relieve themselves. They might ignore your garden.
Electronic-wise, I don't think anything will keep them out. You certainly don't want to water your garden every few minutes.
In all fairness using a wide area detection system is probably not the best way to achieve your aim. Effectively you are looking to booby trap your garden with what we call Victim Operated devices.
The effect you are looking to achieve (noise etc) is entirely up to you.
what you need to do is find the targetable action to set up your device. The cat will enter your garden through certain routes and some of these will be less prone to accidentally setting it off than others. Determined by what is known as pattern of life. Once you have determined these factors you can set up the device accurately, using pressure plates etc, unlike PIR or other motion sensors these are more discriminate.
Electrocute one cat and see what the SPCA does to you. What a cat can get bit by, a kid could too.
Be smart and get a fence!
Sprinklers are better but if the cats turn it into a game your garden will flood.
Anything that shoots can also miss. If all that does is ruin some veg then you get off light.
How many ways could loud noises in the night go wrong?
If you can put a chicken wire dome over the garden (hoop construction) then you can keep birds out too. Remember to put something in the ground all around to stop diggers and have a good door.
put up a couple motion sensors.
replace a light bulb with a relay
turn on a common irrigation valve, couple bucks at the hardware store. often 12 or 24v
connect with a sprinkler head or two.
you and the plants will like the extra watering.
cats, not so much.,
if you want more audio. put in a foot valve that will let the sprinkler drain. that way, the water will be preceded with the air rushing out of the nozzle and a hiss.
